1. Cellular Wireless Networks
Many people use mobile stations, such as cell phones and personal digital assistants (PDAs), to communicate with cellular wireless networks. These mobile stations and networks typically communicate with each other over a radio frequency (RF) air interface according to a wireless protocol such as Code Division Multiple Access (CDMA), perhaps in conformance with one or more industry specifications such as IS-95 and IS-2000. Wireless networks that operate according to these specifications are often referred to as “1×RTT networks” (or “lx networks” for short), which stands for “Single Carrier Radio Transmission Technology.” Another CDMA protocol that may be used is known as Evolution Data Optimized (EV-DO), perhaps in conformance with one or more industry specifications such as IS-856, Release 0 and IS-856, Revision A. Other protocols may be used as well, such as Global System for Mobile Communications (GSM), Time Division Multiple Access (TDMA), WiMax, iDEN and/or any others.
These networks typically provide services such as voice, Short Message Service (SMS) messaging, and packet-data communication, among others, and typically include a plurality of base stations, each of which provide one or more coverage areas, such as cells and sectors. When a mobile station is positioned in one of these coverage areas, it can communicate over the air interface with the base station, and in turn over one or more circuit-switched and/or packet-switched signaling and/or transport networks to which the base station provides access.
The base stations for these networks are typically not associated with any subscriber or small group of subscribers in particular; rather, they are placed in publicly-accessible locations and are used by the service provider's customers generally. These base stations collectively blanket cities, rural areas, etc. with coverage; as such, they are referred to generally and herein as “macro (or macro-network) base stations” and the network they collectively form—or to which they collectively belong—is referred to generally and herein as the “macro network.”
Mobile stations and macro base stations conduct communication sessions (e.g., voice calls and data sessions) over frequencies known as carriers, each of which may actually be a pair of frequencies, with the base station transmitting to the mobile station on one of the frequencies, and the mobile station transmitting to the base station on the other. This is known as frequency division duplex (FDD). The base-station-to-mobile-station link is known as the forward link, while the mobile-station-to-base-station link is known as the reverse link.
2. Femtocells
Many macro-network subscribers, including private consumers and small businesses, among others, in addition to having wireless service (which may include data service) for their mobile station (or mobile stations), also have high-speed (a.k.a. “broadband”) Internet access through another communication channel, which may be cable-modem service, digital-subscriber-line (DSL) service, satellite-based Internet service, and/or some other option.
In an exemplary arrangement, a user may have a cable modem connected (a) via coaxial cable to a cable provider's network and (b) via Ethernet cable to a wireless (e.g., IEEE 802.11 (WiFi)) router. That router may include one or more Ethernet ports to which computers or other devices may be connected, and may also include wireless-access-point functionality, providing a WiFi packet-data interface to, as examples, laptop computers, digital video recorders (DVRs), appliances, and/or any other computing devices or their wireless network adapters.
To address gaps in macro-network coverage (e.g., in buildings) and for other reasons, macro-network service providers have recently begun offering consumers devices referred to herein as femtocells, which may also be referred to as femto base stations, femto base transceiver stations (BTSs), picocells (pico base stations, pico BTSs), microcells (micro base stations, micro BTSs), Low-Cost Internet Base Stations (LCIBs), and by other names. Note that the aforementioned terms that end in “cell” may also be generally and herein used to refer to the coverage area provided by the respective device. Note also that “low-cost” is not used as a limiting term; that is, devices of any cost may be categorized as LCIBs, though most LCIBs typically will be less expensive on average than most macro-network base stations.
A typical femtocell may be approximately the size of a desktop phone or WiFi access point, and is essentially a low-power, low-capacity version of a macro base station. Thus, a typical femtocell will use a normal power outlet, perhaps with a transformer providing a DC power supply. The femtocell may have a wired (e.g., Ethernet) or wireless (e.g., WiFi) connection with the user's router, and would thus have connectivity to the Internet and/or one or more other packet-data networks via the user's broadband connection. A femtocell may establish a virtual-private-network (VPN) connection over the Internet with an entity (e.g., a VPN terminator) on the wireless-service (macro-network) provider's core network, and thereby be able to securely communicate via the VPN terminator with other entities on that core network and beyond.
The femtocell also has a wireless-communication (e.g., CDMA) interface that is compatible with the user's mobile station(s), such that the femtocell may act as a micro base station, providing coverage on the wireless-service provider's network via the user's Internet connection. Usually, a femtocell will provide service on a single RF carrier (or on a single carrier per technology, where multiple technologies (e.g., 1×RTT and EV-DO) are supported), and also transmit what is known as a pilot beacon, which includes administrative messages and parameters that mobile stations use to connect with the femtocell.